82 
Actinozoa — Corals , etc. 
Gallery, 
No. 8. 
Holothu- 
roidea ; (sea- 
cucumbers). 
from the Carboniferous and Silurian rocks, are very well repie- 
sen ted hero. 
5. The Holothuroidea , which have no hard test, properly so 
called, and in which the body is vermiform, have small plates 
and spicules scattered through the skin. Those of Synapta 
(shaped like microscopic anchors) and of Chirodota (like minute 
wheels) have been found by washing the decomposed shales ot 
the Carboniferous limestone of the East of Scotland. . 
Narrow Gallery, No. 9 on Plan (seep. 108 ).— This is retained 
for study purposes, and contains also the Geological Library. 
Gallery No. 10 on Plan— This is the third of the wide 
Galleries, and contains upon its A estern side : 
Sub-Kingdom 4 . — CCELENTERATA. 
Class 19. — Actinozoa (Rayed Animals). 
Gallery, 
No. 10 
on Plan, 
West side. 
Corals. 
Wall-cases, 
Nos. 1-6. 
Table-cases, 
Nos. 1-9. 
This group embraces the “Sea Anemones,” the Alcyonaria, 
and the true corals. 
The Sea Anemones have no hard parts or skeleton, and 
are therefore unknown in a fossil state, but they serve admirably 
to exemplify by their soft parts the structure of the coral - 
P ° lj The cylindrical body of the Sea Anemone is tough, flexible, 
and elastic, with a sucker-like expansion at the base, by which 
it attaches itself to rocks, &c. The month is placed on the 
„ ummit, and is encircled by numerous flexible retractile ten- 
tacles, resembling when expanded the petals of a flower. 
The mouth leads directly into the stomach, which opens 
below into the general visceral cavity. The space surrounding 
the stomach is divided into a number of compartments by a 
series of radiating vertical partitions known as the “mesen- 
teries,” which take their rise from the inner surface of the body 
wall, and are attached to the external surface of the stomach; 
they are also continued downwards to the base of the visceral 
cavity, although less largely developed. 
The spaces between the mesenteries are connected with t he 
general visceral cavity beneath the stomach. 
Division A. — Zoantharia-sclerobasica.* 
Alcyonaria. 
In the Alcyonaria the polypes live together united by a 
common tissue(called the “ coenosarc ”) ; each polype has eight 
* Sclerobasica from sTcleros , hard, and basis, a pedestal : applied to a coral 
haviiwa solid axis which is invested by the soft parts of the animal. 
